Transmission of electrical impulses.



BEST AVAELABLE COP? No. 647,!75. Patented Apr. 10, 1900. F. BEDELL.

TRANSMISSION OF ELECTRICAL IMPULSES.

(No Model.) 2 Sheets-Sheet Wzi'rzwses:

WW W W by 62%. My

E NORRIS was 00 mumrrno. WILSHINGYOL n. c.

T AvAzLAsLE com No. 647,!75. Patented Apr. I0, [900. F. BEDELL.

TRANSMISSION OF ELECTRICAL IMPULSES.

(Application filed m 22 1899.) (No man. 2 Sheets-Sheet 2.

oooooooooooolzoo' cal/cs m5 mums PCI'ERS ca. mom-117m, wnsmnamn. u. a,

BEST AVAILABLE COP:

UNITED STATES.

PATENT CFFICE.

FREDERICK BEDELL, or ITHAOA, NEW YORK;

TRANSMISSION OF ELECTRICAL IMPULSES.

SPECIFICATION forming part of Iietters Patent N 0. 647,17 5, dated April 10, 1906. Application filed May 22, 1899. Serial No. 717,736. (No model.)

To all whom it may concern:

Be it known that I, FREDERICK BEDELL, a citizen of the United States,residin g at Ithaca, county of Tompkins, and State of New York, have invented certain new and useful Improvements in the Transmission of Electrical Impulses, of which the following is a specification, reference being made to the accompanying drawings, wherein-- Figures 1 to 6 illustrate, diagrammatically, the principles of myinvention. Figs. 7 to 12 illustrate difierent wave forms which the currentimpulses may assume. Fig. 13 illustrates a form of apparatus which may be employed to carry out my invention, and Figs. 14: and 15 represent modified features which maybe employed in connection with such apparatus.

My invention relates to the transmission of impulses of current over any desired circuit, but is particularly adapted for the transmission either by land-line or submarine cable of telegraphic currents in which the succeeding impulses are combined and modified in a predetermined manner so as to send intelligible messages according to a specified code.

In the art of telegraphy it has heretofore been common to transmit positive and negative impulses over a circuit so combined as to afiord a means of communication in conformity with a prescribed code. been proposed to transmit a series of alternating-current impulses of a uniform frequency and to interrupt the alternating current thus introduced into the circuit at the zero-points in accordance with a prearranged co e.

In neither one of the two methods just mentioned am I aware that it has been attempted to modify or vary the wave form of the current impulse to meet particular circuit conditions, while in the second method of the two the interruption at the zero-point has heretofore occurred at the moment of the greatest self induction, when the current wave is changing from positive to negative, or vice versa, at the highest rate, the curve of electromotive force being comparatively steep on either side of the zero-line. These alternating-current impulses are also derived from a dynamo-electric machine in which it is not easy to vary the form of the electromotiveforce wave which the machine will naturally It has also produce, and, moreover, since the machine gives an inflexible succession of alternating impulses it is impracticable to utilize difierent wave lengths of current as elements of a code. Thus the code elements may consist of one, two, or more impulses divided by but one rise from zero to maximum and one corresponding fall from maximum to zero. In other words, if we take the wave curve of two or more succeeding impulses and bridge from the crest of one wave to that of the succeeding wave we might eliminate the self-induction due to all of the current variation embraced by such a bridge.

It is the object of my invention to provide a system of transmitting current impulses by means of which the current may be interrupted at the zero periods, and in which the impulses 'may be prolonged to any desired degree, and in which also the form of the wave may be modified as desired and, more particularly, may have, when desired, a long graduated zero-space during which it maybe broken at a period of minimum self-induction, and consequently with the minimum spark at the contact. Moreover, I provide a system wherein the inductive disturbances due to current variations are confined to the external line-circuit and eliminated from the source of electromotive force. In consequence of the characteristics above mentioned and the continuity of the impulses I am enabled to employ ahigher voltage and secure a higher speed of transmission than would be other wise possible, the rapidity being further increased by the employment of impulses of different durations in the formation of a code.

I provide in my system any desirable source of direct current and derive therefrom a series of direct-current impulses by including and excluding in a cyclic order a set of graduating resistances which may severally have any desired value, which may even be changed or varied from time to time, so that the succeeding impulses may have a corre- BEST AvAaAsLE cop;

sponding wave form, and particularly may come, when desired, to a graduated zero, so

thatatthezero-pointthe circuit may bebroken with the least unfavorable eifects, due to inductive and electrostatic disturbances, which may be comprised in the term line reaction. I also provide an apparatus by which, while the current impulses are transmitted in an invariable sequence, it is yet possible at desired points to suppress'the elfect of the resistances or maintain a direct connection from battery to line, and thus suppress the modifying eifect of the resistances on the current from the crest of one impulse-wave to that of the next or other succeeding wave, and thereby in effect multiply the normal wave length by two, three, or any desired number. I

Referring to Fig. l of the drawings, let A represent a battery or any other convenient source of direct current which is to be transmitted over a circuit formed by the line-wires B and C to act upon a receiving apparatus D. An ordinary rheostat or adjustable resistance R is shown as included in the circuit in series with the receiver D. It will be evident that if the-movable contact E-of the rheostat R were caused to reciprocate back and forth over the series of contact-plates of the rheostat R a succession of current impulses would be transmitted over the circuit corresponding to the movement of the contact E and the variation'between minimum and maximum in the amount of resistance thereby included in the circuit.

The basis of my invention is the transmission, by means of any suitable apparatus, of current impulses, such as would result from the arrangement illustrated in Fig. l or one embodying the same princip1e,-and it is evident that by giving special values to the several sections of rheostat R impulses having any required wave form' may be secured at will.

Turning to Fig. 2 of the drawings, I have there shown the contact-plates of rheostat R arranged in a semicircle and connected, respectively, to similar plates forming the complementary semicircle. The contact E is shown as a radial arm journaled concentric-' ally with the series of plates and sweeping over them as it rotates, being driven by. any suitable mechanism, such as a belt F, from a pulley G, which in turn maybe driven by an electric motor or any other agency having a uniform rate of movement. This arrangement will give the same result as would be secured by the reciprocation of contact E in Fig. 1 and illustrates one method of securing a succession of impulses by a continued rotary movement of the transmitter.

Referring to Fig. 3, the rheostat R is shown as shunting both the battery A and the receiver D, and it is evident that in this manner also there will be a series of impulses transmitted to the circuit by the reciprocation of the contact E of the rheostat R, a short circuit being prevented by the resistance R in the line from the battery, as shown.

In Fig. 4 there is -the same .arrangement which appears in Fig. 3, except that the contact E is arranged for rotary instead of reciprocating movement. Again, as indicated in Fig. 5, the rheostat R is partly in series and partly in shunt with the receiver D, and in Fig. 6 the same arrangement is shown, with the provision of a rotary instead of a reciprocating contact E, while I have also shown asecond set of rheostat-sections R, connected to the right-hand half of the circular series of contact-plates, so that the rising currentwave may be differentiated from the falling wave, as shown in Figs. 11 and 12, by inserting one series of rheostat-sections and withdrawing another series.

In general I desire it'to be understood that I do not intend to limit myself in regard to the particular means employed for transmit ting the rheostatically-graduated impulses over the circuit, but may employanysuitable means for securing that result. I would add, however, that I now prefer a device of the general character indicated in Figs. 5 and O, with the rheostat partly in series and partly in shunt with reference to the circuit.

Referring to Fig. 7, there is shown therein a curve of impressed electromotive-force im-' pulses, which appears as a succession of triangles, this being the form which would re-' suit from a complete uniformity in the series of rheostat-sections and a uniform reciprocation of the contact E. If, however, the sections at and near the two extremities of the series have a smaller value than the others, theangles of the curve shown in Fig. 7 will be rounded oif, as shown in Fig. 8, and by the same means the curve may be further modified to the form shown in Fig. 9. By the employment of difierent sets of rheostat-see tions for the rising and falling parts of the wave, respectively, as shown in Fig. 6, it may be made to assume the form shown in Fig. 11 or even that shown in Fig. 12.

For utilizing electric current of the form I have described in the transmission of telegraphic messages I may employ any suitable circuit-breaker arranged to interrupt the circuit at the zero-points of the current accord ing to a determined code. Thus I may employ the well-known form of transmitter consisting of a perforated tape running over a metallic cylinder, so as to pass under a brush normally bearing upon such a cylinder, and thus interrupt the connection between the brush and-cylinder, except where the perforations may occur in the tape. be fed synchronously with the rotation of the contact E, described above, and the perforations will be so spaced as to interrupt the circuit at such points of zero-current as may be necessitated by the requirements of the code and the message which is being sent. I prefer, however, to add toasimple apparatus of this kiud a second row of perforations in The tape will BEST AVAILABLE COP;-

e47,17s a the tape which will controla second contact I spring or brush arranged; to short-circuit or otherwise eliminate the effect of the impulsecontrolling resistance above described. j By this means I may so arrange the second row of perforationsin the tape asto practically suppress at desired points and for desired -periods the modifyingefiect of the said resistances upon the currentandthereby prolong. toanydcsired extent any current impulse or impulses in the'series employed for the transmitted message, the wave then being somewhat as appears in Fig. 10. I

Referring to Fig. 13, H represents a tape such as I have described passing over a metallic cylinder J and having therein two rows of perforations, while two contact-springs K and L bear on the cylinder above the tape in line with the respective rows of perforations. The cylinder J forms the terminal of line 13, while the contact-spring K is connected to contact E and the spring L is connected directly to negative terminal of battery A, whose positive terminal is connected to line 0. Ohviously the connections maybe reversed, the positive battery-terminal being connected to 'spring L and the negative to the line. If the spring K were permanently in contact with the cylinder J, the line would be closed and the continued operation of the contact E wopld'transm-it in the manner already de- 'scribed'i'fconnection 'w'iih'Flgst band das'e ries of impulses of a uniform character, such as is-indicated at Fig. 13, butsuch impulses would be modified or suppressed in a definite manner by any series of perforations in the tape II which might pass under the spring K, such perforations being timed and spaced so that the unperforated parts of the tape will come under spring K at the instant when the currentis at its minimum or at zero. Thus considering only the spring K and the line of perforations in the tape shown in the figure there would be (see Fig. 13") a transmission of impulse 1, a suppression of impulse 2, a transmission of the first halfof impulse 3 and the last half of impulse 4, with a suppression of the last half of impulse 3 and the first half of impulse 4, and so on, the suppression corresponding to the unperforated part of the tape and the transmission to the perforated part. Simultaneously, however, with the action of spring K there is the action of the spring L, connected directly to the terminal of battery A, so as to connect the battery di rcctly to line when bearing upon its own line of perforations in tape ll. Therefore, as shown in the figure, the suppressing effect of spring K at the last half of impulse 3 and the first half of-impulse 4 is neutralized by the spring L, which at the same instant comes over a perforation in the tape, so to continue the currentflow, which would have been interrupted by the spring K it it alone were operating. 'lhus the cllcct of the spring L is to bridge from the crest of impulse-wave 3 to that of impulse-wave 4, as is indicated.

-terial.

by the full lines in Fig. 13. In the same manner spring L comes in again to bridge the impulse-waves 9, 10, and 11. Consequently the resultant eifect will be a series of impulses having the form shown by the full-line curve of Fig. 13". Thus there will be a normal impulse followed bya zero-space, then an impulse of twice the normal length, followed again by a zero-space, then two impulses of normal length, another space, then an impulse of three times the normal length, then another space, and so on. I therefore have available as codeelements current impulses either of the normal length or of any multiple thereof, together with zero-spaces of any desired length. lVith those available elements-I can use a code that is very brief with respect to the range of indication which it afiords.

; The same indicating value may be assigned to a long impulse as is assigned to the several component impulses which would occur during the same period if the impulse were not sustained by means of the brush L. In this case the deleterious effects of self-inductionthat are inseparable from the multiplicity of short impulses are avoided, as mentioned above. This enables me to transmit more rapidly than would be otherwise possible. In cases'where the circuit conditions permit a succession of single impulses these may be employed as code elements as well as the corresponding sustained impulses, a still greater rapidity of transmission being thus made possible on acconntofthebriefer code thereby obtained.

I In the'foregoing description I have for simplicity shown an arrangement wherein one complete revolution of the contact-arm produces one cycle or impulse of electricity from zero to full value andagain to zero. It is commonly desirable, however, to obtain more than one cycle or impulse from one revolution of the arm. Y

In Fig. 14 I have shown the resistance R as connected to four sets of contact-plates arranged in sequence around a circle, so that a contact-arm in sweeping over them mayintroduce and withdraw the resistance four times at each rotation, the platesbein g crossconnected somewhat after the manner of a cross-c0nnected commutator.

Instead of the form of resistance which I have'shown, wherein the graduation is secured by sections of resisting-wire included in or excluded from the circuit in succession, I may employ a resisting-conductor and r range the contact-arm to sweep over it from end to end, so as to give a finer graduation. Thus in Fig. 15, It represents an inlaid ring of carbon set into a block K of insulating ma- The carbon ring may have an irregular cross-seclion, so that its resistance may have any desired value at dificrent points of its length. The arm la will sweep over the carbon ring, and thereby include in or exclude the resistance from the circuit in the resistance of one half will be included in and the resistance of the other half withdrawn from the circuit when it is desired to have the two halves of the current-wave of dilTerent form.

It will be understood that in using the expression graduated resistance I intend to include such graduation as would be accorded by the apparatus illustrated in Fig. 15 and that the cyclic series of impulses I have described is not limited to a succession of impulses that are uniform in period, value, or wave form, since these may be modified,as I have shown, to make up a code for the transmission of communications. Itis to be also understood that I do notin this case make claim to any of the apparatus I have shown and described, since such apparatus hasbeen held to constitute a separate and independent invention from the method vhich I do claim; but I still regard the said apparatus as my invention and as subject to patent protect-ion in due form without prejudice by reason of its disclosure herein for illustrating my method.

What I claim as new, and desire to secure by Letters Patent, is-

1. The method of telegraphing which consists in transmitting over a circuit a series of rising and falling current impulses derived from a sustained source of electromotiv force,whereby the ind uctive disturbances due to variation of current are eliminated from that portion of the circuit comprised within said source and confined to the portion of the circuit external. thereto, and combining said impulses according to a prearranged code.

2. The method of telegraphing which con sisr's in impressing on a circuit impulses of electromot-ivc force of. rising and falling value and of adjustable wave form, adjusting said wave form to suit circuit conditions and transmitting certain impulses in accordance with a prearranged code to a suitable receiver at a distant point. r

3. The method of telegraphing which consists in deriving from the same source of unidirectional elect-romotive force a series of direct-current impulses having a-gradually rising and falling value and transmitting certain impulses according 'to a predetermined code to a suitable receiver at a distantpoint.-

4. The method of tclegraphing which consists in transmitting over a circdit a series of direct-current impulses, each impulscbcing derived from the same source of sustained unidirectional electromotiveforce as the preceding and having a gradually rising and falling value, and interrupting the circuit at moments of zero-current according to a predetermined code.

5. The method of t-elegraphing which co n sists in deriving from a battery,or othcrsource of maintained direct current, a series of diroot-current in'ipulseshaving a graduall y ris- 6. The method of telegraphing which con- I sists in impressing upon a circuit a cyclic series of impulses of electromotive force by periodically modifying by means of graduated resistances the effect on the circuit of a source of electromotive force connected thereto, varying the wave form of the impressed electromotive force by adjusting the values of the 80,

several portions of the modifyingresistauces, transmitting certain current impulses accordin g to a predetermined code and receiviu g the same by a telegraphic receiver.

7. The method of telegraphing which consists in transmitting over a circuit a series of current impulses of one polarity, rising and falling in value with a minimum rate of change when at or near the zero-points, and

interrupting the circuit at moments of zerocurrent according to a predetermined code.

.8. The method of telegraphing which consists in transmitting over a circuit current impulses of one polarity having a gradually rising and falling value and combining impulses or different lengths according to a predetermined code.

9. The method of transmitting a series of current impulses over a circuit which consists in impressing a gradually rising and falling electromotive force on the circuit and pro-- ,longing certain of the current impulses by impressing a constant electromotive force be tween succeeding maximum points of the rising and falling sequence.

10. The method of transmitting a series of current-i mpulses over a circuit which consists in periodically modifying the effect of a source of electromotive force connected to the circuit so as to impress a gradually rising and, falling electromotive force on the circuit and prolonging certain of the current impulses by impressing a constant electromotive force between succeeding points of the rising and falling sequence.

.11. The method of transmitting a series of current impulses which consists in periodically modifying by means of a graduated resistance the effect of a source of constant elecr tromotive force connected to a circuit so as red 13. The method of telegraphing which consists in impressing a series of impulses of elec tromotive force upon an electric circuit by continuously inserting and withdrawing graduated resistances between the circuit and a source of sustained electromotive force, and transmitting select-ed currentimpulses according to a predeterminedcode.

14. The method of telegraphing which consists in impressing a series of impulses of electromotive force upon an electric circuit by repeatedly modifying by means of a continuously-operated rheostat the efiect of a source of sustained electromotive force connected to the circuit, and transmitting selected current impulses according to a predetermined code.

15. The method of telegraphin g which consists in impressing a series of impulses of electromotive force upon an electric circuit by periodically connecting the line-circuit to terminals connected to a source of sustained eleetromotive force arranged in a series of successively greater and lesser potential, and transmitting selected impulses acccording to a predetermined code.

16. The method of telegraphing which consists in deriving from a source of unidirectional electromotive force a continuous and uninterrupted series of unidirectional-electromotive-force impulses, impressing code-determined electromotive-force impulses upon a circuit and transmitting corresponding currentimpulses to suitable receiving apparatus.

17. The method of telegraphing which consists in transmitting over a circuit a series of current impulses, interrupting the circuit according to a predetermined code at moments 3 5 when the current is changing at a minimum rate, and receiving the transmitted impulses by suitable receiving apparatus.

18. The method of telegraphin g which consists in impressinga series of impulses of electromotive force upon an electric circuit by periodically modifying the eifect of a source of sustained electromotive force connected to the circuit and interrupting the circuit between said impulses according to a predetermined code.

19. The method of telegraphing which consists in transmitting over a circuit a series of current impulses rising and falling in value FREDERICK BEDELL.

Witnesses:

LUZERNE CovILLE, FRED I-I. SMITH. 

